dominated government that is still violating human rights, Brad Adams, Asia director at Human Rights Watch, said before the president arrived in the region.

Obama's aides said he was determined to lock in democratic changes already under way, but would also press for further action, including freeing remaining political prisoners and stronger efforts to curb ethnic and sectarian violence.

A senior U.S. official said Obama would announce the resumption of U.S. aid programmes in Myanmar during his visit, anticipating assistance of $170 million in fiscal 2012 and 2013, but this, too, would be dependent on further reforms.

The president will be announcing that the United States is re-establishing a USAID mission in Burma, which has been suspended for many years, the official told reporters in Bangkok, declining to be named.

The United States has softened sanctions and removed a ban on most imports from Myanmar in response to reforms already undertaken, but it has set conditions for the full normalisation of relations, such as the release of all political detainees.

Asked if sanctions could be lifted completely at this stage, a senior administration official insisted they could not. All these things are reversible, he said.

PRISONER RELEASE

In a move clearly timed to show goodwill, the authorities in Myanmar began to release dozens of political prisoners on Monday, including Myint Aye, arguably the most prominent dissident left in its gulag.

Some 66 prisoners will be freed, two-thirds of them dissidents, according to activists and prison officials.

The government will also let the International Committee of the Red Cross resume prisoner visits, according to a statement late on Sunday, and the authorities plan to devise a transparent mechanism to review remaining prisoner cases of concern by the end of December 2012.

In a speech to be given at Yangon University to an audience that will include several high-profile former prisoners, Obama will stress the rule of law and allude to the need to amend a constitution that still gives a great role in politics to the military, including a quarter of the seats in parliament.

America may have the strongest military in the world, but it must submit to civilian control. As President and Commander-in-Chief, I cannot just impose my will on our Congress, even though sometimes I wish I could, he will say.

He looks forward to a future where national security is strengthened by a